Piston-ring pot-casting and method of making piston-rings therefrom



C. A. MARIEN. PISTON RING POT CASTING AND METHOD OF MAKING PISTON RINGSTHEREFROM. APPLICATION FILED APR.15I 1920.

,94,630 Patented Oct. 25, 19210 CHARLES A. MARIEN, or sr. LOUIS,MISSOURI.

PISTON-RING POT-CAQTING AN D METHOD OF MAKING- PISTON-RINGS THEREFBOM.

Specification of Letters Patent.

Patented Oct. 25, 31921.

Application filed April 15, 1920. Serial No. 374,094.

To all whom it may concern:

Be it known'that 1, CHARLES A. MARIEN, a citizen of the United States,residing at St. Louis, State'of Missouri, have invented certain new anduseful Improvements in Piston-Ring Pot-Castings and Methods of MakingPiston-Rings Therefrom, of which the following is a full, clear, andexact description, reference bein had to the accompanyin drawings,forming apart hereof.

he present invention is directed to improvements in piston-ring potcastings and the manufacture of piston-rings therefrom, the objectsought being to provide a casting which will yield the precise qualityof metal that a piston ring should possess to serve as an effectivepacking and lubricator I for the piston on which the same is mounted.

0n the other li As well understood in the art piston rings are casteither individually, or in the form of pots or tubes from which theindividual rings are afterward cut. Each method has its advantages andits disadvantages. lVhere the rings are cast individually the danger ofa sudden chilling of the .metal is imminent, such sudden chilling givingrise to an undesirably hard casting which has the effect of cuttxing thewalls of the cylinder.

nd the rings cut from the conventional pot casting are apt to be softand lack resiliency so that they do not form a perfect packing. Theseshortcomings result from a lack of proper control over the cast metalwhile cooling in the mold, the individually cast ring 'being apt tochill too suddenly and become ard by reason of an excess of combinedcarbon, and the pot casting on account of the thickness of its wallscooling slowly and causing the carbon to separate out as graphite,thereby not only imparting to the casting an undesirable softness butimpairing its resiliency to such an extent as to impair the usefulnessof the metal for purposes of a packing ring. Under my invention I cast apot or tube, on the inside of which are disposed a plurality of annularconcentric ribs or ring formations corresponding to the cross-section ofthe piston ring desired, these ribs being connected by a comparativelythin outer shell forming the peripheral wall of the pot, which may bereadily severed or cut off from the series of ribs or rings by theapplication thereto of a suitable cutting tool, the rings thus Severedrequiring only to be split and finished after the usual manner offinishing piston rings, whether cast individually or sliced from a potcasting: By the peculiar cross-section of the walls of my improved potthe cooling of the casting is more rapid along the thin portions of theouter shell by which the rib formations are. connected, the lattercooling at a comparatively slower rate than said connecting portions,the resultant period of cooling for the casting being such as to enableme to carefully regulate the temper, hardness, and tensile strength ofthe casting, thereby-producing a ring which possesses the necessaryresilience, hardness and wearing qualities of a piston ring especiallywhere the same is intended to operate in the c linder of an internalcombustion engine. T e advantages of my improved pot casting will bemade apparent ,from the following detailed description of the inventionin connection with the accompanying drawings in which view of the pistonring as severed from the:

casting and subsequently split; Fig. 5 is a face View of the split ring;and Fig. 6 is a modified form of the invention with the ring formationscast .in the outside of the ot. p Referring to the drawings, 1represents the head-stock, 2 the tail-stock, 3 the mandrel, 4 the toolcarriage and 5 the tool of any conventional form of lathe, the mandrelbeing held in position between the head chuck 6 and the spindle 7 of thetail-stock as well understood in the art. In the illustration here shownone end of the pot-casting passed over the mandrel is likewise held bythe jaws 8 of the head-chuck 6. The pot casting com prises a tubular orcylindrical shell 9 on the inside of which are formed a ser es ofannular ribs or rings 10, spaced su1table distances apart, the depth ofeach ring, that is to say the dimension measured radially from the axisofthe cylinder, corresponding to the thickness of the piston ring, andthe width of the ring or the dimension measured parallel to the axis ofthe cylinder, corresponding to the width of the piston ring.

The thickness of the shell 9 from the inner walls of which the severalrings or ribs pro ject is in the present example substantially one halfthe thickness of the ring, the inner boundary of the shell beingindicated by the dotted lines 00 (Fig. 2).

By mounting the casting on the mandrel 3 and imparting rotation theretoas well understood in the art, and applying the cutter 5 tothe end ofthe shell, it follows that with a rotation of the casting and alongitudinal advance of the cutting tool, the latter will shave off themetal constituting the shell 9 proper, and by the time the cutter hasreached a depth indicated by the line m which corresponds to an elementof the inner cylindr1cal surface of the shell, it will have completelysevered from the shell a ring 10, the rings being severed one at a timeas the cutting tooladvances from the tail-stock to the head-stock Aseach ring is severed it may be moved out of the way by moving it alongthe mandrel toward the tail-stock (Fig. 1). Assuming that the shellproper is one-sixteenth of an inch thick it is probable that a singletraverse of the cutting tool may not shave off that thickness of metaland it may be necessary for the tool to pass a second time overthecasting to shave off the necessary thickness of metal to sever orrelease the rings. In the diagram Fig. 3, the dotted circle representsthe original outer boundary of the shell, and the hatched layer 23 whichthe tool is shaving from the ring 10 represents the thickness of metalleft after a previous layer had been shaved off, the removal of thelayer 25 completely releasing the ring 10 from the shell. It will beseen from Fig. 2 that the annular ribs 10 form complete piston ringblanks, and only require the removal of the thin outer shell 9 to adepth indicated by the lines w to be released or severed from thecasting. After the ring blanks are severed or released from the shellthey are split so as to leave a gap a and then finished in any of thewell known Ways practised in the art. In the casting of a potwith a thinshell of which the rings form an integral part, the casting neithercools too slowly nor too rapidly as a whole. It is true that the thinwalls of the shell between the rings will chill more quickly than thethicker Walls opposite the rings, but the cooling rate of the latterwill be more or less under control of the former which cannot be thecase where the rings are cast individually; and, where pot castings areof auniform thickness corresponding to the thickness of the rin s therewe have an excess of metal which b requlres more time to cool than willassure for the ring the desired resiliency, the slower cooling due tothe excess metal tending to produce rings which are too soft andyielding to hug the cylinder walls with sufiicient pressure to insuregood packing. By therefore providing a cross-section of pot castingwhich insures against a too sudden cooling of the molten metal on theone hand, and a too prolonged cooling'on the other, we can eliminate theobjections to which the individual cast piston ring and the conventionalpot casting give rise, and thereby provide a casting in which thethickness of the outer shell relatively to the cross-section of the ringmay be so proportioned that a perfect casting may be secured, possessingall the requisites of temper, tensile strength, resiliency, andhardness, and other qualities which an ideal piston ring should possess.

The illustration Fig. 2 shows a pot with rings substantially one-eighthinch thick,

one-quarter of an inch wide and three and one-half inchesin diameterwhen compresed to working size. In that case the outer shell would beabout one-sixteenth of an inch thick. These relative dimensions ofcourse are only by Way of example and may be varied in practice asclearly obvious to the skilled mechanic. The manner of holding the potin the lathe is immaterial, but in the present example the mandrel isheld at the center of the chuck head 6, and one end of the casting isgripped by the jaws of the chuck so that the mandrel and casting mayrotate as a unit, it being observed that the mandrel does not hold thecasting with a drive fit. Other methods of mounting the casting in alathe may be resorted to, so long as it may be rotated and the cutter 5may advance longitudinally along the work to shave off the outer shellof the casting. In Fig. 1 we see that the cutter has made one traversealong the casting, the cut thus made leaving a shoulder 71. at the chuckend of the casting. The cutter is now making its second traverse tocompletely shave off the outer .shell and release the rings. Two of thesevered rings are shown on the right moved toward the end of themandrel. The

shifting of the severed rings of course is not necessary, but the sameare here shown moved to one side to better brin out the operation of thecutting tool. T e spaces between the ribs in the example before us areapproximately one-half the width of the ring, but I do not wish to beunderstood as 'being restricted to this dimension as practicalconsiderations may require a different spacing between the rings. Thecasting of the rin s or ribs 10 on the outside of the shell ,ig. 6)instead of on the inside as shown (Figs. 1, 2 and 3) would come withinthe spirit of my invention.

Having described my invention what I claim is 1. A piston-ring potcasting comprising a tubular shell, and a series of ring formationsdisposed circularly about the axis of the shell and spaced apart.

l ll

2. A piston-ring pot casting comprising an outer tubular shell, and aseries of ring formations disposed circularly on the inside of the shelland spaced apart.

3. A piston-ring pot casting comprising an outer cylindrical shell, anda series of ring formations disposed circularly on the inside of theshell and spaced apart.

- 4. A piston-ring pot casting comprising an outer cylindrical shell,and a series of ring formations disposed on the inside of the shell, theradial dimensions of the side faces of the rings or portions leadingfrom the inner Wall of the shell corresponding substantially to thedimensions of the sides of the piston ring.

5. A piston-ring pot casting comprising a series of concentric ringsspaced apart and disposed about a common axis, and an outer shellconcentric With said axis connecting the rings.

6. A method of manufacturing pistonrings Which consists in forming a potcasting or tube having a series of ring formations disposed on theinside and spaced apart, mounting said tube in position for engagementwith a cutter, and causing the cutter to traverse the Walls of the tubeaxially, circumferentially,and radially toward the axis of the tubethereby severing the shell of the tube from the rings and releasing therings.

In testimony whereof I ailix my signature, in presence of two Witnesses.

CHARLES A. MARIEN. Witnesses ,EMIL STAREK,

Jos. A. MICHEL.

